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Strange change to engine number

Submitted by shane_harvey1 on Tue, 03/01/2023
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Nortons - General

Background: My 1967 650ss was produced in April of 1966 and subsequently imported to Berliner in US. I bought it from the late Morrie Gauger in 1986.

After nearly 37 years, I now noticed an odd thing about the engine number, it reads 18 M 117(XXX) with the frame being 18 117(XXX) (matching#s). M?!? Close inspection shows the engine number to be legit except the 'M' which is punched over a mostly peaned out 'SS'. This would not change anything legally as that goes by the frame number. Since the rest of the engine number is clearly not overstamped or modified in any way, what could possibly be the reason for the change that was made?

Submitted by david_cooper on Tue, 03/01/2023

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Mercury was Sept 68.  

I imagine the model type was probably stamped on the cases during engine build  and the 6 digit frame number only added after it had been united with the frame.  So anything stamped on the case in front of 116XXX was for convenience in the factory.

Submitted by shane_harvey1 on Tue, 03/01/2023

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The motor was originally stamped 18 SS as I stated. There was an attempt to erase this by peaning the SS over, but with a bit of photographic trickery it still can be seen. The M was then stamped over this. The bike is definitely a 650 SS which is one of the reasons this change is so odd.

Submitted by philip_hannam1 on Tue, 03/01/2023

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All but one of the Mercury 650 engines started with 129*** so I think this suggestion can be ruled out.

In January 1965 – a special batch of 50 Manxman 650 Nortons were built and sent to Berliner. These being between engine numbers 111651 and 111850.  The exact trim specification  is unknown as we are now into the time of AMC production and record keeping which was minimal.

Does this 117***  Norton have any digits stamped at the back of the engine?

No, that's it. The only other markings I have found are for the case halves toward the bottom - each the number 1.

Submitted by robert_tuck on Wed, 04/01/2023

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M for Morrie ?,  If you marked your bits you were much more likely to be able to ID parts if stolen. Over the years many sins have been perpitrated , My old red/dove  88Deluxe is now swanning around in 650 ss  trim and colours and was sold as an 88ss   a few years back.

Submitted by howard_robinson on Wed, 04/01/2023

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Hello all - Happy New Year.  I once had a Matchless G15 engine that had an M prefix to the engine number but that was a 750.  I also had a Mercury that had a suffix M to the gearbox number. Like Phil said this began 129*** .  I suspect that the Matchless/AJS Atlas Hybrids had M numbers somewhere to avoid confusion and 66/67 is around that period.  However I have never heard of a Factory-produced Hybrid with a 650 Dominator engine. good luck Shane, howard  

Ha ha, I actually considered that possibility. Over the years he dealt with a lot of old bikes and parts for them, so I don't see him spending the time to modify this, but not impossible. Since I can't ask him, this mystery may remain just that.

 

 


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